Timing of exposure to somatostatin relative to growth hormone-releasing factor dictates the rat anterior pituitary cell growth hormone response.

The temporal interactions of rat GH-releasing factor (GRF) and somatostatin (SRIF) on the secretion of GH from perifused rat anterior pituitary cells have been studied. SRIF and GRF were employed at concentrations in a range close to levels reported in the hypophysial circulation of the rat. GH secretion was inhibited by pulses of 1 nmol SRIF/l (6 min) or 0.

Anticonvulsants inhibit rat neuronal somatostatin release.

Somatostatin (SRIF), a peptide widely distributed in the central nervous system, has been implicated in the genesis of seizure activity in a number of animal models of epilepsy. We examined the effects of the anticonvulsants, phenytoin, carbamazepine and diazepam, on the release of SRIF from dispersed adult rat neuronal cells in short-term culture. Each of these agents caused dose-dependent inhibition of ouabain-stimulated SRIF release in a well-characterized hypothalamic dispersed cell system.

Pre-exposure of rat anterior pituitary cells to somatostatin enhances subsequent growth hormone secretion.

The precise roles of GH-releasing factor (GRF) and somatostatin (SRIF) in the orchestration of pulsatile GH secretion have not yet been fully determined. We examined the interactions of rat GRF and SRIF in the concentration ranges present in rat hypophysial-portal blood, on the secretion of GH from dispersed male rat anterior pituitary cells in monolayer culture. The effects of exposing cells to GRF and/or SRIF (0.

Effects of vasopressin on insulin secretion and inositol phosphate production in a hamster beta cell line (HIT).

The recent isolation of vasopressin (VP) from the rat and human pancreas led us to investigate the effects of VP on insulin secretion. In the SV 40-transformed hamster beta cell line (HIT), 0.1-1.

Inhibition of hypothalamic somatostatin release by beta-adrenergic antagonists.

A number of in vivo studies suggest that hypothalamic somatostatin (SRIF) tone is stimulated by the beta-adrenergic system. Employing dispersed adult male rat hypothalamic cells, we studied the effects of beta-adrenergic antagonists on the release of hypothalamic SRIF. Propranolol, at concentrations of 1-100 microM, had no detectable effect on basal SRIF release, but caused dose-dependent inhibition of SRIF release stimulated by ouabain.